Would be better if it were optional. The little key in the status area is more than enough indication for me. A persistent notification is not a notification, it's a hack.
The hack is the aggressive battery optimization in some phones that don't respect the native Android battery optimization settings and still kill apps.
I get it, and i guess the fault is on Google for not providing an alternative for such apps. Still a hack though, because such things don't belong in the user's notifications.